Electrochemical and electromechanical properties of superior-performance hybrid polymer actuators exhibiting synergistic effects due to manganese oxide and multi-walled carbon nanotubes on various ionic liquids

Abstract

The electrochemical and electromechanical properties of poly(vinylidene fluoride-co-hexafluoropropylene) actuators were investigated using a non-activated multi-walled carbon nanotube (MWCNT)–ionic liquid (IL) gel electrode containing manganese oxide (MnO₂) on various ILs. The MnO₂/MWCNT/IL actuators surpassed the strain and maximum generated stress performance observed for the only-MWCNT and only-SWCNT actuators on all ILs. These actuators are different from only-MWCNT and only-SWCNT actuators, which act solely as electrostatic double-layer capacitor (EDLC) units. The frequency dependence of the displacement responses of the MnO₂·xH₂O/MWCNT/IL polymer actuators was successfully simulated using a double-layer charging kinetic model. Two parameters for the simulation were determined: the strain at the low frequency limit and the time constant. Simulations of the electromechanical response of the MnO₂·xH₂O/MWCNT/IL actuators predicted strains at low frequencies as well as at the associated time constant, confirming that the model is applicable not only to EDLC-based actuator systems but also to the fabricated EDLC/FC system. These results suggest that flexible, robust films, fabricated from metal oxides and MWCNTs that function synergistically, are potential candidates for actuator materials that can be applied in wearable and energy conversion devices.